temperature   global Warming      
 Equilibrium is the Reality 
 
 Saturation is the Proof 
 
 
 The Fakery of Modern Global Warming Science 
     

Gary Novak

Global Warming Home

About

Introduction

What, How and Why

List of Points

A Sociology Problem

Key Summaries:
How Modern Global Warming Science Took Form

Why Global Warming Science is Nothing but Fraud

Saturation, Proof of Climate Science Fraud

Fudge Factor for Settled Science

Fakery of the Primary CO2 Effect

Criminal Standards of Science

Background Principles:
Errors in Claims
Crunching the Numbers
Absorption Spectra
Explanations
Simple Words
Contrivance
Communication Corruption

Alphabetical Page List
And Summaries
Detailed Specifics:
Stefan-Boltzmann

Firing Scientists

Thermometer Fraud

Fake Ice Core Data

Equilibrium in Atmosphere

Acid in the Oceans

Oceans not Rising

Future Ice Age

"Delicate Balance" Fraud

Heat-Trapping Gases

The Cause of Ice Ages and Present Climate

Climategate

Second Climategate

The Disputed Area

IPCC Propaganda

The Water Vapor Fraud

Back Radiation is Absurd

The 41% Fraud

The 30% Fraud

A Fake Mechanism

Global Dynamic

River, not Window

What about Argo

Heinz Hug Measurement

Hockey Stick Graph

Ice Melt


                

Global Warming and Nature's Thermostat

by Roy W. Spencer
Climate Scientist

This is text without graphics.
The original with graphics is here. (external)

Introduction
Here I (Roy Spencer) present a simplified (but hopefully accurate) explanation of the basics of global warming - call it a global warming primer. First, I will address the issue of how warm we are today, and some possible explanations for that warmth. Next, I'll briefly describe the Earth's natural greenhouse effect and global warming theory. Finally, I will explain the "thermostatic control" mechanism that I believe stabilizes the climate system against substantial global warming from mankind's greenhouse gas emissions. Some of what I will present is an extension of Richard Lindzen's "infrared iris" effect, support for which has been recently found in satellite measurements.

Warming Over the Last Century
There is little doubt that globally averaged temperatures are unusually warm today (at this writing, 2007). While a majority of climate researchers believe that this warmth is mostly (or completely) due to the activities of mankind, this is as much a statement of faith as it is science. For in order to come to such a conclusion, we would need to know how much of the temperature increase we've seen since the 1800's is natural. So, let's examine current temperatures in their historical context. Over the last 100 years or so (see Fig.1) globally-averaged surface temperature trends have exhibited three distinct phases.

Fig. 1. Globally averaged surface temperature variations (deg. C) over the last century (through 2006) have shown warming until about 1940 (which must have been natural), then a slight cooling until the 1970's (either natural or the result of aerosol pollution), then steady warming since the 1970's (J. Hansen, NASA/GISS).

The warming up until 1940 represents the end of the multi-century cool period known as the "Little Ice Age" which was, historically, a particularly harsh period for humanity. This warming must have been natural because mankind had not yet emitted substantial amounts of greenhouse gases. Then, the slight cooling between 1940 and the 1970's occurred in spite of rapid increases in manmade greenhouse gases. One theory is that this cooling is manmade -- from particulate pollution. Finally, fairly steady warming has occurred since the 1970's. It should be noted that there is still some controversy over whether the upward temperature trend seen in Fig. 1 still contains some spurious warming from the urban heat island effect, which is due to a replacement of natural vegetation with manmade structures (buildings, parking lots, etc.) around thermometer sites.

Warming Over the Last Millenium
Thus, at least in the context of the last century or more, today's global temperatures are unusually warm. But when was the last time that the Earth was this warm?. You might have heard claims in the news that we are warmer now than anytime in the last 1,000 years. This claim is based upon the "Hockey Stick" temperature curve (Fig. 2) which used temperature 'proxies', mostly tree rings, to reconstruct a multi-century temperature record. That "warmest in 1,000 years" claim lost much of its support, however, when a National Acadamy of Science review panel concluded in 2006 that the most that can be said with any confidence is that the Earth is warmer now than anytime in the last 400 years. (Note that this is a good thing, since most of those 400 years occurred during the Little ice Age.)

Fig. 2. The Mann et al. (1998) proxy (mostly tree ring) reconstruction of global temperature over the last 1,000 years is believed to have erroneously minimized the warmth of the Medieval Warm Period (MWP).

But it turns out we don't need to use "proxies" for temperature like tree ring measurements -- there are actual temperature 'measurements' that go back over 1,000 years. 'Borehole' temperatures are taken deep in the ground, where the seasonal cycle in surface temperature sends an annual temperature "pulse" down into the Earth. A measurement and dating of these pulses from Greenland (Fig. 3) reveals much warmer temperatures 1,000 years ago than today.

Fig. 3. The GRIP (Greenland) borehole record is one of the best records because it is not a proxy, it is a DIRECT measure of temperature. Shown are the last 2000 years. (Dahl-Jensen et al. 1998, Science, 282, 268-271 "Past Temperatures Directly from the Greenland Ice Sheet"). A similar reconstruction occurs for the Ural Mountain borehole temperatures (i.e. warmer 1000 years ago, Bemeshko, D., V.A. Schapov, Global and Planetary Change, 2001.

Note that such methods for dating temperatures cause a "smearing" of the signal in time. Because of this smearing effect, decadal-time scale temperature "spikes" probably occurred during the MWP which are smoothed out in Fig. 3. If we could see those temperature spikes that undoubtedly occurred during the MWP, our current warmth would seem even less significant.

Thus, we see that substantial natural variations in temperature can, and do, occur -- which should be no surprise. So, is it possible that much of the warming we have seen since the 1970's is due to natural processes that we do not yet fully understand? I believe so. To believe that all of today's warmth can be blamed on manmade pollution is a statement of faith that assumes the role of natural variations in the climate system is small or nonexistent.

If We Can't Explain It, It Must Be Human-Induced
The fact is, science doesn't understand why these natural climate variations occur, and can not reliably distinguish between natural and possible human influences on global temperatures. So, if scientists have no other natural explanation for a warming trend, they tend to assume that it is manmade. And it is indeed possible to explain the temperature changes over the last 100 years by carefully tuning climate models with some estimated effects from volcanic eruptions, sunlight intensity variations, manmade aerosol emissions, and greenhouse gas increases. But this is simply one possible explanation -- one that largely ignores possible natural sources of temperature variability.

As a result, how worried we are about global warming is directly related to how much faith we have that natural climate variations (for instance, a small change in low-level cloudiness) are not substantially contributing to our current warmth. "When all you have is a hammer, everything looks like a nail." Global warming is our hammer, and so every change we see in the climate system that we can not otherwise explain tends to look like a nail.

Climate Prediction and Weather Forecasting Are Not the Same
Before describing the greenhouse effect and climate models, we first need to clear up a common misconception about forecasts of global warming. There are two quite different kinds of forecasting of atmospheric behavior: weather prediction, and climate prediction. Weather prediction involves measuring the state of the atmosphere at a given time and then using a computer program containing equations (a 'numerical model') to predict how the weather will evolve in the coming days. Simply stated, these 'initial condition' models extrapolate the measured atmospheric behavior of the atmosphere out into the future. They have been quite successful at short ranges (a few days), and their skill is slowly improving over time, but that skill drops to close to zero at about 10 days.

In contrast to weather prediction models, the purpose of climate models is not to get a good 3 day or 10 day forecast. Climate models are instead run for much longer periods of simulated time - many years to centuries. Their purpose is to determine how the model's climate (average weather) is affected when one of the rules -- 'boundary conditions' -- by which the atmosphere operates is changed in the model.

In the case of global warming, that rule change is mankind's addition of greenhouse gases, mainly carbon dioxide from the burning of fossil fuels, which then affects the model's 'greenhouse effect' -- the way in which the model atmosphere processes infrared (radiant heat) energy.

The Earth's Natural Greenhouse Effect
Global warming is all about mankind's small enhancement of the Earth's natural 'greenhouse effect'. The greenhouse effect refers to the trapping of infrared (heat) radiation by water vapor, clouds, carbon dioxide, methane, and a few other minor greenhouse gases (see Fig. 4). You can think of the greenhouse effect as a sort of 'blanket' -- one that operates on infrared radiation rather than by physically trapping warm air beneath it like a regular blanket does. The natural greenhouse effect makes the lower atmosphere warmer, and the upper atmosphere cooler, than it would otherwise be without the greenhouse effect.

Fig. 4. The Earth's natural 'greenhouse' effect is due to the absorption of infrared (heat) radiation by water vapor, clouds, carbon dioxide, methane, and other greenhouse gases in the atmosphere.

Mankind's Enhancement of the Greenhouse Effect
The most common explanation for global warming goes like this: Mankind's addition of carbon dioxide to the atmosphere disrupts the Earth's radiative energy balance (see Fig. 5) by reducing its ability to radiatively cool to outer space. Energy balance refers to the expectation that all of the Earth's absorbed sunlight (the energy input) is balanced by an equal amount of infrared radiation that the Earth emits back to outer space (the energy output). It is estimated that this input and output, averaged over the whole Earth over several years, is naturally maintained at a value of around 235 Watts per square meter (W/m2).

Fig. 5. The Earth's radiative energy balance is fundamental to understanding global warming theory, which says that mankind's greenhouse gas emissions is disrupting the 235 W/m2 balance (solar input & infrared output).

But mankind's emissions of greeenhouse gases is believed to have disrupted that balance. Since the beginning of the industrial revolution, it is estimated that the normal infrared cooling rate of 235 W/m2 has been reduced by about 1.6 W/m2. Taking into account the warming that has already occurred (supposedly) in response, one estimate is that a 0.8 W/m2 imbalance still exists today. That continuing imbalance represents further warming that must occur, even if we were to stop producing greenhouse gases immediately. Of course, since mankind continues to emit greenhouse gases, a radiative imbalance will continue to exist, and so warming will continue as well.

Interestingly, the Earth-orbiting instruments for measuring the Earth's radiative components are not quite accurate to measure the small radiative imbalance that is presumed to exist. That imbalance is, instead, a theoretical calculation.
 
You might also be surprised to find out that the direct effect of this imbalance (often called a 'radiative forcing') from the extra CO2, by itself, would have very little effect on the Earth's temperature. If everything else in the climate system remained the same, a doubling of the atmospheric carbon dioxide concentration (probably late in this century) would cause little more than 1 deg. F of surface warming. The effect is so small because, even at CO2 doubling, the fraction of our atmosphere that carbon dioxide occupies is still less than 1 part in 1,000.

Obviously, a 1 deg. F warming would cause little concern - if that was the whole story. The problem is that everything else probably doesn't remain the same.

Positive or Negative Feedbacks?
Almost all of the scientific uncertainty about the size of manmade global warming is related to how the climate system will respond the small (1 deg. F) warming tendency. The atmosphere could dampen the warming tendency through 'negative feedbacks'-- for instance by increasing low-level cloudiness. Or, it could amplify the warming tendency through 'positive feedbacks', for instance by increasing the water vapor content of the atmosphere (our main greenhouse gas), or by increasing high-altitude cloudiness.

Most computerized climate models behave in this second way, amplifying the initial warming by anywhere from a little bit, to a frightening amount (over 10 deg. F by 2100). So, you can see then that is very important to determine how sensitive the climate system is to the radiative forcing from the extra greenhouse gases we are putting into the atmosphere.

To be able to predict how much warming there will be, what we really need to know then is the kind of negative and positive feedbacks that exist in the climate system. The net effect of all of the feedbacks together determines what is called the 'climate sensitivity', which as the name implies, expresses how much surface warming would result from a given amount of radiative forcing - say, a doubling of the concentration of carbon dioxide in the atmosphere.

Estimating Climate Sensitivity
It would be very helpful if we could do a laboratory experiment to determine how the Earth will respond to mankind's addition of greenhouse gases to the atmosphere - but we can't. There is only one 'experiment' going on, and we are all part of it.

If we can't do a laboratory experiment, another way to estimate climate sensitivity would be some previous example of climate change in response to radiative forcing. For instance, there are pretty good estimates of how much the Earth cooled after the major eruption of Mt. Pinatubo in the Philippines in June, 1991 (see Fig. 6). The millions of tons of sulfur dioxide that was injected into the stratosphere by Mt. Pinatubo spread around the Northern Hemisphere, and reduced the amount of incoming sunlight by as much as 2% to 4% The resulting cooling effects lasted two or three years, until the sulfuric acid aerosols finally dissipated.

Fig. 6. The explosive 1991 eruption of Mt. Pinatubo in the Philippines injected millions of tons of sulfur dioxide into the stratosphere. The resulting 2%-4% reduction in sunlight offered a natural test of the Earth's climate sensitivity to changes in solar radiation.

Unfortunately, an estimate of climate sensitivity from changes in sunlight is not necessarily the same as the sensitivity to changes in greenhouse gases, which affect infrared light. While sunlight is the source of energy for the climate system, greenhouse gases affect how that energy courses through the climate system. Very simply put, sunlight causes weather, but the greenhouse effect is the result of weather.

So, are there any previous examples of infrared (greenhouse) climate forcings? There are ice core measurements from Antarctica which suggest that, hundreds of thousands of years ago, carbon dioxide levels and temperature did indeed go up and down together. But there is much debate over which was the cause, and which was the effect. Based upon the available evidence, the current consensus of opinion is that the temperature changes preceded the carbon dioxide changes by a century or more. Temperature changes causing carbon dioxide changes might be explained by the fact that warmer water can not hold as much carbon dioxide, so periods of climatic warming led to a slow release of oceanic CO2. Thus, in contrast to volcanic eruptions and their effect on solar heating, we are possibly left without a natural example of infrared radiative forcing, which is what global warming is all about.

But the climate models suggest it does not really matter. They suggest the climate has about the same sensitivity to solar heating changes as to infrared cooling changes. If that is true, then natural events like the Pinatubo eruption could indeed be used to estimate manmade global warming. But I believe that the climate's sensitivity to solar forcing is not the same as its sensitivity to infrared forcing. And here's why....

What Determines the Earth's Natural Greenhouse Effect?
Sunlight is the source of energy for our weather, and so it makes sense that more (or less) sunlight will make the Earth warmer (or cooler). But the greenhouse effect's infrared heat trapping does not 'cause' weather - instead, weather causes the greenhouse effect! Remember, most of the Earth's greenhouse effect is due to water vapor and clouds, and so it is the weather (winds, evaporation, precipitation, etc.) that controls the strength of the natural greenhouse effect.

This cause-versus-effect role of the Earth's natural greenhouse effect is an important distinction. I mentioned above the common explanation that the Earth's "energy balance results in a roughly constant globally-averaged temperature". But I believe that this has cause and effect turned around: It is more accurate to say that "the atmosphere generates a greenhouse effect and temperature that results in energy balance" with the incoming sunlight.

But Don't Climate Models also "Generate" a Greenhouse Effect?
If the climate models have the correct physics in them, then such differences in how we conceptualize the problem won't matter. But unless we understand the processes that control the Earth's natural greenhouse effect, climate modelers risk putting too much emphasis on physics that don't matter that much, at the expense of ignoring physics that end up having a controlling influence on climate.

As it is, even climate 'experts' give faulty physical explanations for how manmade global warming works. For instance, the largest and most consistent positive feedback exhibited by these models is positive water vapor feedback. The common explanation for this feedback is that the warming tendency from the extra carbon dioxide causes faster evaporation of water from the surface...and since water vapor is the atmosphere's dominant greenhouse gas, this faster evaporation leads to an amplification of the warming tendency from the extra CO2.

This simple explanation has great appeal, and is widely repeated by climate modelers. But it is grossly misleading. The average amount of water vapor that resides in our atmosphere is not controlled by evaporation. Instead, it is controlled by precipitation (rain and snow) systems. Even though water is continuously evaporating from the surface of the Earth, the atmosphere never fills up with it because precipitation systems remove it long before saturation is reached.

Precipitation Systems: Nature's Air Conditioner?
I believe that it is precipitation systems that ultimately control most of the Earth's natural greenhouse effect. All of the air in that portion of the atmosphere where weather occurs (the troposphere, which contains 80% of the atmosphere's mass) is continuously being recycled through precipitation systems (see Fig. 7). Winds in the troposphere's 'boundary layer' pick up water vapor that has been evaporated from the surface, and then transport this vapor to precipitation systems, where an equal amount of vapor (on average) is removed as rain or snow.

Fig. 7. Most of the atmosphere gets continuously recycled through precipitation systems, which determine the moisture properties, and thus greenhouse effect, of the air.

But here's the part that even climate researchers tend to forget: For all of the moist air flowing into the precipitation systems in the lower troposphere, an equal amount of air must be flowing out of those same systems, mostly in the middle and upper troposphere. (The exception is thunderstorm downdrafts, which you have likely experienced before). That air flowing out has moisture (water vapor and cloud) amounts that are controlled by precipitation processes within the systems. Thus, precipitation processes within clouds have a controlling influence on the greenhouse effect.

At this point some scientists will protest, "But that's only in the vicinity of the precipitation systems!" No, not at all...precipitation systems exert control over the greenhouse effect -- at least the water vapor portion -- far beyond the immediate vicinity of those systems - in fact, over the entire Earth. For instance, the cloud-free, dry air that is slowly sinking over the world's deserts got its dryness from air flowing out the top of precipitation systems. Eventually, that air will leave the desert, pick up moisture evaporated from the land or ocean, and be cycled once again through a rain or snow system.

Similarly, the cold air masses that form over continental areas in the wintertime are extremely dry because the air within them came from the upper troposphere after it had been exhausted out of a rain or snow system. It this were not the case, wintertime high pressure systems would become saturated with water vapor as the air radiatively cools to outer space.

Thus, we begin to see that much of the Earth's natural greenhouse effect is under the control of these systems. It doesn't matter whether they are tropical thunderstorms, or high latitude snowstorms, it is still the air flowing out of them in the upper troposphere that determines the humidity characteristics of the cloud-free regions everywhere else.

...And There's More....
And the precipitation system's control of the the climate system doesn't even end there. They also indirectly control cloud amounts in other regions. The heat trasported upward in precipitation systems largely determines the vertical temperature profile of the troposphere. The temperature profile, in turn, exerts a strong influence on cloud systems. For instance, there are vast areas of marine stratus clouds in the lower troposphere that form over the eastern ends of the subtropical oceans where cold water wells up from below (see Fig. 8). Those clouds form because the moist air from ocean evaporation gets trapped below a temperature inversion (warm air layer). That warm air is there because it has been sinking in response to moist rising air in precipitation systems, some possibly thousands of miles away.

Fig. 8. Marine stratocumulus clouds, which cool the climate system by reflecting sunlight, are partly under the control of precipitation systems far away.

It should be increasingly clear to you that we can not know how sensitive the climate system is to mankind's small enhancement (from extra greenhouse gases) of the Earth's natural greenhouse effect (mostly from water vapor and clouds) unless we understand precipitation systems. Unfortunately, precipitation is probably the least understood of all atmospheric processes.

In a little-appreciated research publication, Renno, Emanuel, and Stone (1994, "Radiative-convective model with an explicit hydrologic cycle, 1: Formulation and sensitivity to model parameters", J. Geophys. Res., 99, 14429-14441) demonstrated that if precipitation systems were to become more efficient at converting atmospheric water vapor into precipitation, the result would be a cooler climate with less precipitation. Thus, precipitation systems have the potential to be, in effect, the Earth's 'air conditioner', switching on when things get too warm.

The big question is, do they behave this way or not?

Precipitation in Climate Models
Climate model representations of precipitation processes are very crude. In fact, for warm air masses, the models don't actually grow precipitation systems. They instead use simple 'parameterizations' that are meant to statistically represent the net effects of precipitation on the atmosphere. There is nothing inherently wrong with using parameterizations - as long as they represent the feedbacks that exist in the real atmosphere. What we really need to know is how the efficiency of precipitation systems changes with temperature.

Unfortunately, relatively little testing of the climate models has been done in this regard. Most of the emphasis has been on getting the models to behave realistically in how they reproduce average rainfall, not how the model handles changes in rainfall efficiency with warming.

Recent research with satellite observations (in review for publication as of 7 March 2007) suggests that when the tropics become unusually warm for a few days or weeks at a time, precipitation systems there produce less high-altitude ice clouds. This, in turn, reduces the natural greenhouse effect of the tropical atmosphere. This reduction in high-altitude cloudiness causes enhanced infrared cooling to outer space, which then results in falling tropical temperatures.

This is a natural negative feedback process that is counter-intuitive for most climate scientists, who believe that more tropical rainfall activity would cause more high-level cloudiness, not less. Whether this process also operates on the long time scale involved with global warming is not yet known, and will surely be the subject of considerable debate.

A Summary, and the Future
It is now reasonably certain that changes in solar radiation cause temperature changes on Earth -- for instance, the 1991 eruption of Mt. Pinatubo caused a 2% to 4% reduction in sunlight, resulting in two years of below normal temperatures. It is not so obvious, however, that small changes in the Earth's infrared cooling from mankind's burning of fossil fuels will do the same. This is because the Earth's natural greenhouse effect is mostly under the control of weather systems: specifically, precipitation systems. Either directly or indirectly, these systems determine the moisture (water vapor and cloud) characteristics for most of the rest of the atmosphere.

Precipitation systems thus act as a thermostat, causing cooling when temperatures get too high (and warming when temperatures get too low). It is amazing to think that the ways in which tiny water droplets and ice particles combine in clouds to form rain and snow could determine the course of global warming, but this might well be the case.

I believe that it is the inadequate handling of precipitation systems -- specifically, how they adjust atmospheric moisture contents during changes in temperature -- that is the reason for climate model predictions of excessive warming from increasing greenhouse gas emissions.

I predict that further research will reveal some other cause for the warming we have experienced since the 1970's -- for instance, a change in some feature of the sun's activity. In the meantime, a high priority research effort should be the study of changes in precipitation systems with changes in temperature -- especially how they confer moisture charateristics to the atmosphere as air is continuously recycled through them.

Fortunately, we now have several NASA satellites in Earth orbit that are gathering information that will be immensely valuable for determining how the Earth's climate system adjusts during natural temperature fluctuations. It is through these satellite measurements of temperature, solar and infrared radiation, clouds, and precipitation that we will be able to test and improve the climate models, which will then hopefully lead to more confident predictions of global warming.


Roy W. Spencer received his PhD in meteorology at the University of Wisconsin-Madison in 1981. He has been a Principal Research Scientist at the University of Alabama in Huntsville since 2001, before which we was a Senior Scientist for Climate Studies at NASA's Marshall Space Flight Center where he received NASA's Exceptional Scientific Achievement Medal. Dr. Spencer is the U.S. Science Team leader for the Advanced Microwave Scanning Radiometer flying on NASA's Aqua satellite. His research has been entirely supported by U.S. government agencies: NASA, NOAA, and DOE.

Original Source of This Summary with Graphics (external)
A Look at Modeling
How Roy Spencer's Criticism Differs from Mine

 

           
 
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